Method for controlling a wind turbine by optimizing its production while minimizing the mechanical impact on the transmission

Abstract

A method is disclosed for controlling a wind turbine by optimizing its production while minimizing the mechanical impact on the transmission. The wind turbine comprises a nacelle provided with a rotor on which blades are fastened and an electrical machine linked to the rotor by a transmission in which pitch angle of the blades is controlled, comprising An aerodynamic torque setpoint and an electrical machine torque setpoint making possible maximizing the recovered power are determined from measurements of wind speed, of rotor speed and of electrical machine speed. At least one of the setpoints is modified by subtracting from it a term proportional to a difference between the measured speed of the rotor and the measured speed of the electrical machine. A pitch angle of the blades making possible production of the aerodynamic torque setpoint is determined. The blades are oriented according to the angle of inclination.

The invention claimed is: 
     
       1. A method for optimizing electrical energy production of a wind turbine, the wind turbine comprising a nacelle provided with a rotor on which blades are fastened, and an electrical machine linked to the rotor by a transmission, in which an pitch angle of the blades is controlled, comprising:
 a) determining an aerodynamic torque setpoint and an electrical machine torque setpoint used for maximizing recovered power, from measurements of wind speed, of rotor speed and of the electrical machine speed; 
 b) modifying at least one of the torque setpoints by subtracting a term proportional to a difference between the measured speed of the rotor and the measured speed of the electrical machine to limit moments and fatigue on the transmission; 
 c) determining a pitch angle of the blades making possible production of the aerodynamic torque setpoint; and 
 d) orienting the blades according to the determined pitch angle of the blades. 
 
     
     
       2. A method according to  claim 1 , wherein at least one of the setpoints is modified by:
 i) determining a torque on the transmission resulting from the aerodynamic torque and the electrical machine torque setpoints; 
 ii) determining a resultant torque setpoint by subtracting from the resultant torque a term proportional to a difference between the measured speed of the rotor and the measured speed of the electrical machine; and 
 iii) modifying aerodynamic torque setpoint by dividing the resultant torque setpoint into an aerodynamic torque and an electrical machine torque. 
 
     
     
       3. A method according to  claim 2 , in which the resultant torque setpoint T res   sp  is expressed as:
     T   res   sp   = T     res   −k{dot over (γ)}   tr    
 
       with k being strictly positive calibration parameters, with T res  being the resultant torque, and {dot over (γ)} tr  being a speed of torsion of the transmission, equal to a difference in speed of the rotor Ω r , and of the electrical machine Ω g  related to one axis with 
       
         
           
             
               
                 
                   
                     γ 
                     . 
                   
                   tr 
                 
                 = 
                 
                   
                     Ω 
                     r 
                   
                   - 
                   
                     
                       1 
                       N 
                     
                     ⁢ 
                     
                       Ω 
                       g 
                     
                   
                 
               
               , 
             
           
         
       
       where N is a gear ratio between an axis of the rotor and an axis of the electrical machine. 
     
     
       4. A method according to  claim 1 , in which the pitch angle of the blades is determined by inverting an aerodynamic torque model while using the wind speed and rotor speed measurements. 
     
     
       5. A method according to  claim 2 , in which the pitch angle of the blades is determined by inverting an aerodynamic torque model while using the wind speed and rotor speed measurements. 
     
     
       6. A method according to  claim 3 , in which the pitch angle of the blades is determined by inverting an aerodynamic torque model while using the wind speed and rotor speed measurements. 
     
     
       7. A method according to  claim 1 , in which the proportional term is determined by using a model of dynamics of the transmission. 
     
     
       8. A method according to  claim 2 , in which the proportional term is determined by using a model of dynamics of the transmission. 
     
     
       9. A method according to  claim 3 , in which the proportional term is determined by using a model of dynamics of the transmission. 
     
     
       10. A method according to  claim 4 , in which the proportional term is determined by using a model of dynamics of the transmission. 
     
     
       11. A method according to  claim 5 , in which the proportional term is determined by using a model of dynamics of the transmission. 
     
     
       12. A method according to  claim 6 , in which the proportional term is determined by using a model of dynamics of the transmission.